FIG. 2 shows a control structure of a related motor controller. Reference numeral 21 designates a motor control section, 22 designates a model control section, 23 designates a speed control proportional gain, 24 designates a differentiator, 25 designates an integrator, 26 designates a speed control proportional gain of the model control section, 27 designates an integrator showing inertia of the model control section and 28 designates an integrator. Further, Vref designates a speed command, Vfb designates a motor speed, Tref designates a torque command, STref designates a time integrated value of the torque command, Vfb′ designates a model speed and STref′ designates a time integrated value of the model torque command.
The related motor controller includes the motor control section for controlling the motor speed and the model control section for simulating a speed control by a model to identify the inertia by the ratio of a value STref obtained by integrating the torque command of a speed control section by a time to a value STref′ obtained by time-integrating the torque command of the model control section (see Patent Document 1). Further, a related motor controller also includes a motor control section for controlling a motor speed and a model control section for simulating a speed control by a model to identify inertia J by the ratio of a time integrated value of the torque command STref obtained by time-integrating a filtered value of the torque command Tref of the motor control section in prescribed sections [a,b] shown in FIG. 4 to a time integrated value of the model torque command STref′ obtained by time-integrating the torque command Tref′ of the model speed control section in the same sections, and adjust the speed gain Kv of the motor control section based on the identified inertia J (see Patent Document 2).    Patent Document 1: International Patent Application Laid-Open No. 1996/37039 pamphlet (see page 6, FIG. 1)    Patent Document 2: JP-A-2001-218488 (see page 2, FIG. 1)